To start off you need to find the amount of koalas there are at the current number of trees by using the ratio one to 3 which means there is one koala for every 3 gum trees. So you need to devide 252 by 3 giving you the answer of 84 koalas currently. Now you nees to find how many koalas there are for the future 345 trees based on the same ratio 1 to 3. This would give you 115 koalas to be expected in the future. Finally to find the amount of koalas increaed you need to subtract 84 from 115 giving you a final answer of 31 koalas.
This can be answered using simple logic. The questions is asking for the length of the hypotenuse. The hypotenuse is the biggest side. solve for all the answers to find your answer.